<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script>
			var miu = 0;
			var timer;

			function begin() {
				clearInterval(timer);
				timer = setInterval(function() {
					miu += 0.01;
					document.getElementById("div").innerHTML = miu.toFixed(2);
				}, 10);
			}
			function over(){
				miu=0;
				clearInterval(timer);
			}
			function reset(){
				miu=0;
				clearInterval(timer);
				document.getElementById("div").innerHTML="0"+"0"+":"+"0"+"0";
			}
		</script>
	</head>
	<body>
		<div id="div">00:00</div>
		<button onclick="begin()">开始</button>
		<button onclick="over()">结束</button>
		<button onclick="reset()">重置</button>
	</body>
</html>
